diff --git a/libraries/base/dp/src/vhdl/dp_block_validate_bsn_at_sync.vhd b/libraries/base/dp/src/vhdl/dp_block_validate_bsn_at_sync.vhd
index 47cb45bade13a28402e6d47080299feca2963957..7f11d113cf10a2b4504d089f5d924f97098ab9cb 100644
--- a/libraries/base/dp/src/vhdl/dp_block_validate_bsn_at_sync.vhd
+++ b/libraries/base/dp/src/vhdl/dp_block_validate_bsn_at_sync.vhd
@@ -199,37 +199,37 @@ BEGIN
     -- Using v_bsn_at_sync to ensure correct behavior when in_sosi has no latency compared to bs_sosi.
     VARIABLE v_bsn_at_sync : STD_LOGIC_VECTOR(g_bsn_w-1 DOWNTO 0); 
   BEGIN
-    v_bsn_at_sync := bsn_at_sync_reg;     
-    v_bsn_ok      := bsn_ok_reg;
-    out_valid     <= out_valid_reg;
- 
+    v_bsn_at_sync    := bsn_at_sync_reg;     
+    v_bsn_ok         := bsn_ok_reg;
+    out_valid        <= out_valid_reg;
+    cnt_discarded_en <= '0'; 
+
     IF bs_sosi.sync = '1' THEN
-      v_bsn_at_sync := bs_sosi.bsn;
+      v_bsn_at_sync := bs_sosi.bsn(g_bsn_w-1 DOWNTO 0);
     END IF;
 
     IF TO_UINT(in_sosi.channel) = g_check_channel THEN 
-      -- Compare bsn at sync of in_sosi to bsn at sync of bs_sosi.
       IF in_sosi.sync = '1' THEN 
-        IF in_sosi.bsn = v_bsn_at_sync THEN
+        -- Compare bsn at sync of in_sosi to bsn at sync of bs_sosi.
+        IF UNSIGNED(in_sosi.bsn(g_bsn_w-1 DOWNTO 0)) = UNSIGNED(v_bsn_at_sync) THEN
           v_bsn_ok := '1';
         ELSE
           v_bsn_ok := '0';
         END IF;
+
+        -- set cnt_discarded_en to control u_discarded_counter.  
+        cnt_discarded_en <= NOT v_bsn_ok;
       END IF;
 
       -- Setting out_valid to control the discarding at packet level.
       IF in_sosi.sop = '1' THEN
         out_valid <= v_bsn_ok;
       END IF;
-
-      -- set cnt_discarded_en to control u_discarded_counter.  
-      cnt_discarded_en <= in_sosi.sync AND NOT v_bsn_ok;
     ELSE
       IF in_sosi.sop = '1' THEN
         out_valid <= '1'; -- Packets with channel unequal to g_check_channel are always valid
       END IF;
 
-      cnt_discarded_en <= '0'; -- Packets with channel unequal to g_check_channel cannot be discarded.
     END IF;
     bsn_ok      <= v_bsn_ok;      -- bsn_ok is used to indicate if the bsn is correct for the entire sync period of g_check_channel.
     bsn_at_sync <= v_bsn_at_sync; -- register to store the bsn at sync of bs_sosi.
diff --git a/libraries/base/dp/tb/vhdl/tb_dp_block_validate_bsn_at_sync.vhd b/libraries/base/dp/tb/vhdl/tb_dp_block_validate_bsn_at_sync.vhd
index 66b17b21e6b6e30dceac514bc18c57853235de39..74423a7316df7c613d011459ebd4d0d15c3b882c 100644
--- a/libraries/base/dp/tb/vhdl/tb_dp_block_validate_bsn_at_sync.vhd
+++ b/libraries/base/dp/tb/vhdl/tb_dp_block_validate_bsn_at_sync.vhd
@@ -63,7 +63,11 @@ ARCHITECTURE tb OF tb_dp_block_validate_bsn_at_sync IS
   CONSTANT c_gap_size       : NATURAL := 4;
   CONSTANT c_nof_sync       : NATURAL := 5;
   CONSTANT c_nof_blk        : NATURAL := g_nof_blocks_per_sync * c_nof_sync;
-  -- choosing c_check_channel such that it corresponds with a channel from stimuli on a sync because the channel field is generated by a counter.
+  -- The u_stimuli_in creates counter data in stimuli_sosi.channel. Therefore 
+  -- choose some c_check_channel value (> 0, < c_nof_blk) that will occur in 
+  -- the future. Hence this c_check_channel value will occur once in the tb, 
+  -- because stimuli_sosi.channel keeps incrementing. Choosing c_check_channel 
+  -- such that it corresponds with a channel from stimuli on a sync pulse.
   CONSTANT c_check_channel  : NATURAL := g_nof_blocks_per_sync; -- can be c_check_channel MOD g_nof_blocks_per_sync = 0 but not larger than c_nof_blk.
   
   SIGNAL dp_clk             : STD_LOGIC := '1';